Surely any currency only has value, to the extent that users have trust that it will be a reliable store of value. This principle seems to apply to any material object, given the status of money, as well as to any electronic equivalent.

There is very little real value in an arbitrary lump of metal; with a specified shape, composition and surface decoration. Even something like gold is only likely to be melted down and used for something else, if its monetary value is considered to be less than the value of the metal if used for a non coinage purpose.

If the authority which issued the currency is overrun by an enemy, its money will be largely valueless. For example the Confederate dollar only had value after mid 1865 as a curiosity for collectors.

An electronic currency presumably has no value at all if faith in it is lost, since unlike metal or paper currency it cannot be recycled or collected.